Posterior Cruciate Ligament (PCL) Injuries
The PCL and anterior cruciate ligament (ACL) limit the motion of the tibia backward and forward, respectively. The lateral collateral ligament (on the outside of the knee) and the medial collateral ligament (on the inside of the knee) limit side-to-side knee motion.
Each year in the United States, about 25,000 PCL injuries are diagnosed, roughly one-tenth the number of diagnosed ACL injuries. Fifty percent of PCL injuries occur in conjunction with other knee ligament injuries, while the other 50 percent occur alone and are referred to as isolated PCL injuries.
PCL tears usually result from high force impacts, generally vehicular accidents or contact sports such as football, soccer, or hockey. PCL injuries also can occur in non-contact sports, such as gymnastics or skiing, but are much less common.
A PCL injury usually occurs during a direct hit below the knee while the leg is bent. In other cases, you may land directly on a bent knee, driving the tibia up and behind the knee and tearing the PCL. Extreme hyperextension of the leg (straightening beyond the normal limit) is a third type of trauma that may result in tears to the PCL and other knee ligaments.
If untreated, a torn PCL can change knee mechanics, resulting in abnormal motion and subsequent pain and instability. Over years, this wear and tear can lead to progressive degenerative arthritis.
Symptoms of PCL injuries include:
- marked, immediate swelling (within three hours of the injury)
- difficulty in walking after the injury
- pain when moving the knee
- an occasional feeling of instability or the knee “giving way”
Unlike the “pop” and severe pain that may occur with a torn ACL, an isolated PCL injury may manifest itself simply as swelling in the knee that subsides over a few days or weeks. In many cases, patients may overlook the initial injury and fail to visit a doctor or specialist for evaluation. Unlike ACL injuries, isolated PCL injuries may not initially limit knee function, allowing you to return to normal activities.
Diagnosis of a PCL injury begins with an extensive history to learn how the injury occurred. The doctor must determine what position the leg was in at the time of injury and whether the injury involved contact or a noncontact mechanism (for example, twisting). In an acute, isolated PCL injury, there is usually a history of mild pain and swelling. If the PCL and other knee ligaments are torn, the knee is severely swollen and the person is completely disabled.
Once a thorough history is obtained, the doctor performs a physical exam of the knee to assess the stability of the ligaments. Using specific tests, the physician can diagnose PCL injuries by applying forces to the knee and feeling for abnormal motion.
The examiner also must assess other knee ligaments to rule out combined ligament injuries. In severe, multiple ligament injuries, nerves and blood vessels also may be damaged. These injuries must be evaluated immediately by a doctor.
It is difficult at times to completely assess all the damage that may have occurred in conjunction with a PCL injury. In this case, obtaining additional studies such as magnetic resonance imaging (MRI) exams can be very helpful. Magnetic resonance can show the ligaments, cartilage, and bone to give an accurate picture of the extent of the injury.
Treatment for a PCL injury depends on the extent of the patient’s injury, the patient’s age, and the patient’s desired level of activity. A young, active person with a complete PCL tear may require surgery, whereas a sedentary, middle-aged individual with a partial tear may go directly into rehabilitation.
Extensive counselling of the patient by the doctor and therapist must occur before a final decision can be made on treatment. The options for treatment include a nonoperative strengthening program and surgical reconstruction of the damaged ligaments.
- nonsurgical treatment
Nonsurgical treatment involves exercises specifically designed to improve strength, flexibility, and balance. A brace may be prescribed, but unlike ACL-deficient knees, PCL injuries benefit little from braces.
- surgical treatment
Surgery for the PCL-injured knee is more difficult and complex than for the ACL-injured knee. Traditional open-knee surgery or arthroscopic surgery may be used. In arthroscopic surgery, the surgeon uses several small incisions in the knee joint to reconstruct the ligament.
The goals of rehabilitation are to restore range of motion and to strengthen the quadriceps muscles, which help stabilize the knee. After surgery, you may have to use crutches and a knee brace. Exercises such as squats and leg presses are used because they put less stress on the knee. Full recovery takes several months
How can I prevent a PCL Injury?
Athletes can take three steps to reduce their risk of PCL injuries:
- Training and conditioning should be a year-round program. Skill drills and strength and flexibility exercises will enhance balance and coordination so you will be ready when the season starts.
- Make strengthening exercises for the hamstrings and quadriceps muscles a regular part of your conditioning program. To stretch the quads, stand and use a wall or table for support. Lift one leg and pull your foot towards your buttocks. Hold for five seconds, then release the foot and stand straight. Repeat six to ten times on one side, then turn and repeat on the other side.
- To stretch the hamstrings, sit with one knee bent and the other leg extended, toes pointing to the ceiling. Lean forward until you feel a stretch. Hold for five seconds then return to your original position. Repeat six to ten times on each leg.
- Practice proper landing technique (from a jump) and learn to do cutting maneuvers in a crouched posture with a slight bend at the knee and the hip.
Improving Sports Performance
The key to improving sports performance after a PCL injury is proper a rehabilitation program, and adhering to some of those same principles after the injury is gone.
Keep in mind that the single most important aspect of improving performance is stretching before and after you step onto the field, court, ice, or golf course.
Benefits derived from stretching include:
- increased physical efficiency and performance
- decreased risk of injury
- increased blood supply and nutrients to joint structures
- increased coordination
- improved muscular balance and postural awareness
- decreased risk of lower-back pain
- reduced stress
- enhanced enjoyment
As an athlete, your number one concern is getting back to full strength as soon as possible so that you can return to training and competition. That is why appropriate rehabilitation is extremely important.
The goals of rehabilitation are to restore range of motion and to strengthen the quadriceps muscles, which help stabilize the knee. After surgery, you may have to use crutches and a knee brace. Exercises such as squats and leg presses are used because they put less stress on the knee.
Precautions you can take at home for minor PCL injuries include:
- reduce activity during the acute phase
- ice injury multiple times per day
- compression of the knee with a bandage or wrap
- elevation if the knee above the level of the heart
- use anti-inflammatory medications such as ibuprofen to reduce inflammation and speed up recovery
Once swelling subsides, you will need to follow a program of physical therapy to strengthen your quadriceps muscle and regain range of motion.
Some patients require surgery to stabilize the knee. Arthroscopic surgery, which uses small incisions and pencil-sized instruments, is used to determine and repair damage to the cartilage in the knee. Avulsion fractures (tearing away) may need to be fixed with internal screws to ensure proper healing. If the PCL is completely torn, it may be reconstructed using a portion of the patellar tendon or some other autograph.
The major objectives of rehabilitation from a PCL injury are to increase hip and knee flexibility, pain-free range of motion, and strengthen the thigh muscles. In severe cases, you should avoid activity that causes knee pain altogether. In these cases, you can still maintain cardiovascular fitness by swimming or cycling if allowed by your doctor.
In some of the following exercises, both legs are to be used, which is intended to prevent the uninjured leg from developing knee pain. (The uninjured leg is forced to assume some of the workload of the injured one and so is prone to injury.) These exercises may be done more than once daily. Three times daily is best, but work up to this amount gradually.
- Front thigh muscle sets
Sit with legs extended and fully contract the muscles of the front thighs. Hold contractions for 10 seconds. Repeat 10 times.
- Straight-leg raises
Lie with one leg extended and the other bent at the knee. Lift the entire leg from the hip so that the heel is about 5 inches above the floor or ground. Hold this position for 5 to 10 seconds, then slowly lower the leg. Repeat 10 times for each leg.
- Backward leg raises
Lie on stomach with legs straight. Lift one leg as high as possible and hold for 5 to 10 seconds. Repeat 10 to 20 times for each leg.
- Half-knee bends
Stand with feet apart at about shoulder width or as the injury improves, try to stand with feet together. Slowly lower the body weight by bending the knees. Do not perform a full squat but rather stop at about half of the full-squat position and then fully extend the knees. If there is pain before achieving the half-squat position, stop downward travel at that point. Repeat 10 to 20 times.
Once posterior knee pain has been minimized, you may be able to swim, cycle, walk, stair climb, weight train, or jog, as pain allows. These activities will help you to gradually resume your normal training regimen. Remember that stretching, strengthening, and range-of-motion exercises must be continued to reduce the risk of injury recurrence.
During the period when normal training should be avoided, alternative exercises may be used. These activities should not require any actions that create or intensify pain at the site of injury. They include:
- water running
- stationary bicycle (add resistance gradually from one session to the next, as pain allows)
When can I return to my sport or activity?
The goal of rehabilitation is to return you to your sport or activity as soon as is safely possible. If you return too soon you may worsen your injury, which could lead to permanent damage. Everyone recovers from injury at a different rate. Return to your activity is determined by how soon your PCL injury recovers, not by how many days or weeks it has been since your injury occurred. It also depends on how serious the injury is. Instances where reconstructive surgery is required will obviously create a longer recovery period than patients with a strain or knee pain.
A good rule is to allow pain to dictate when you’re ready to return to activity. You should return in moderation, and back off if you feel any pain.
A typical surgery patient may be able to ride a bike at three months, start running at five to seven months, and return to competitive sports after eight to 12 months. Full recovery may take up to two years.
The ultimate goal of PCL reconstructive surgery is to provide dynamic stability while maintaining full range of motion, so that athletes can return to competitive or recreational sports. Progress is assessed by the patient’s perception of how stable the knee feels and by comparing the strength and stability of the injured and uninjured knees.
You may safely return to your sport or activity when, starting from the top of the list and progressing to the end, each of the following is true:
- You have full range of motion in the injured knee compared to the uninjured knee.
- You have full strength of the injured knee compared to the uninjured knee.
- You can jog straight ahead without pain or limping.
- You can sprint straight ahead without pain or limping.
- You can do 45-degree cuts, first at half-speed, then at full-speed.
- You can do 20-yard figures-of-eight, first at half-speed, then at full-speed.
- You can do 90-degree cuts, first at half-speed, then at full-speed.
- You can do 10-yard figures-of-eight, first at half-speed, then at full-speed.
- You can jump on both legs without pain and you can jump on the injured leg without pain.
How long will the effects of the injury last?
With proper rehabilitation, the first occurrence of pain that is diagnosed and treated in its early stages with rest, ice, elevation, and compression usually lasts two weeks. If the injury has recurred several times, full recovery may take as long as six weeks.
Should poor biomechanics be the underlying problem, returning to your sport may take longer. Some athletes with anterior knee pain caused by poor biomechanics of the foot, knee, or hip, find immediate relief from pain once fitted with appropriate and effective orthotic devices or patella tracking braces.
Frequent episodes of PCL injuries may result in a ligament tear. Such a complication may require surgical treatment, and full recovery under such circumstances can take up to two years, depending on the severity.